A gas turbine includes a compressor, combustors, and a turbine. Air taken in from an air intake is compressed by the compressor to become compressed high temperature and pressure air. In the combustor, fuel is fed to the compressed air to cause combustion, and the high temperature and pressure combustion gas drives the turbine, whereby an electric generator connected to the turbine is driven. In this case, the turbine includes plural turbine vanes and turbine blades that are alternately provided in a casing, and an output shaft connected to the electric generator is rotationally driven by driving the moving blades with the combustion gas. In addition, the combustion gas, which has driven the turbine, is converted to have static pressure by a diffuser in an exhaust casing before it is emitted to atmosphere.
The combustors are circumferentially disposed. As described above, the high temperature and pressure combustion gas is generated by feeding the compressed air with the fuel to cause combustion, and is sent to the turbine. At this time, the combustion gas is introduced from transition pieces into the turbine blades and the turbine vanes of the turbine through a turbine nozzle portion. Thus, also the transition pieces are circumferentially disposed. A combustion gas outlet end in each transition piece and the turbine nozzle portion are connected by a flange portion. A circumference of the flange portion is a compressed air passage. Accordingly, a seal member is provided between adjacent flange portions so that the compressed air cannot penetrate a combustion gas passage.
As such a combustor seal structure, for example, the seal structure described in Patent Literature 1. In the combustor seal structure described in Patent Literature 1, along opposing faces of adjacent flanges at transition piece outlet ends, a recess groove across the opposing faces of the flanges is provided, and a seal assembly formed of a seal member and a plate spring is inserted in the recess groove. A pair of consecutive projection portions in the seal member is disposed across the opposing faces of the flanges, toward a combustion gas passage in the recess groove, and is pressed by the plate spring to form a seal face.